Thiazinocyanine dyes



Dec. 24,1940. B. EILENSQN 2,226,153

THIAZINOCYANINE DYES Filedv April 21-I 1957 32o 4o 44 48 52 56 leoomp BY Wg Patented Dec. 24, 1940 n I. n n

Bernard Beilenson, Harrow, Weald, England, vassignor to Eastman vKodak Company;A Rochester, N. Y., a corporation of New Jersey Application April 21, 1937 Serial No. 138,158

. In Great Britain April 24, 1936' 7 Claims. ('61. 26o- 240) This invention relates to new dyesand more nucleus. More specically A can represent an particularly to what can be fcalled thia'zinocya- ,alkyl-1 group, such as methyl, ethyl, or the like, R nine dyesrand to photographic emulsions containand R' can represent alkyl groups, such as mething the same. f .r yl, ethyl, n-butyl, decyl, allyl or f-hydroxyethyl c An object of my invention'is to provide thiazfor example, X can represent an acid radical, 5

inocyanine dyes. A` further object is to provide such as haiide,`alkylsulfate, perchlorate or p-tolu a process for the preparationthereof. en'esulo'nate xfor example, vZ can represent the A still further object iszto provide photographic non-metallic. atomsneces'sary to complete a hetemulsions containing suchl dyes. A still further erocyclic nucleus, such as a fve-membered heterlo object is to provide photographic emulsions sensiocyclic' nuclei, e. gi one of the oXazole serieslike. 10

tized with such dyes.4 .Othermore specific obbenzoxazole, VLl-r'nethyloXazo-le and eor -naphjects will become apparent hereinafter.` thzzazoles; one of 7the thiazole serieslike benzo- My new dyes are derived from either'ZA-benzothiazole,` 5-chlorob'enzothiazole, oror -naphthothiazine (I) or 1,4-benzothiazin'e (II). thiazoles and Ll-phenylthiazole; one ofthe selenw H2v A azolev series; like benzoselenazole, 5-methylbenzo- 15 selenazele fl-phenylselenazole; one of the indolenine series like. 3,3-dialkylindole nines; one-of' the fthiazoline.` series like 4,5-'dihydrothiazole called simplythi'azoline or one of the selenazoline: series like, r4:,5-dihydrosele'nazole calledA 20 simply A selenazoliria or Z 'can represent the non-metallic atoms necessaryto complete a six'-4 memberedheterocyclic nucleus, e. g. one of. the

. v pyridine'series orLone of thequinoline series like 25 N/ 5-methylquinolineor.5,6benzoquinoline (--naph- II., Y" .t thoquinoline). The above names for I. and II. are those em-U fMy le? dyes Canltbefpl 613221161? nlbl ployed-in Richters Lexikon. In Chemical ab- O' a. qlaernarysa". of a" xa y l. C p

r of. either I. or 11. with a cyclammonium quater- 30 stracts I. 1s called 2,4,l-benzoth1az1ne andII. 1s h 1t .na n, acti, am l rou M 30 called 1,4,2-benzothiazine. The nomenclature of a'rya t Co lf'al. mg a re Xe .y gl php l the dyes of my invention Willbe based-ony the lculamy-a'ie'mfe methyl group mit e alp aor gamma position, y1. e. one of the so-called reactivel Lexikon nomenclature. f

. posltions, The condensatlon 1s` advantageously My new dyes can be Called thlazmopseudocy' eectedin rthe presence of a basic condensing as y Y orpotas'sium carbonates, sodium ethylate, potasslum o'r` sodium hydroxides, organic bases, partcularly strong tertiary organic bases, such as trie'thylamine,,tributylamine, triethanolamine or N- methylpipe'ridine forY example, i. e. `an organic 40 base having adissociation constant substantially greater than pyridine.. The condensations can be el'cted' in the preseneoff diluents which are inerttoward the reactants. Lower aliphatic alcohols, i.- e. an alcohol of from one to four carbon-l5 atoms are suitable `as diluents, for example. Ethyl alcohol isadvantageously employed. One molecular proportion of each, the Quaternary salt ofA the S-alkylthiol compound and the cyclammo- To wherein A represents hydrogen or an"organic` nium Quaternary salt containing a reactivealkyl group, D represents a vinylene Aor phnylene groupwith tvvo molecular proportions of con.

group, R and R representorganicgroups, Xrepdensing agent are advantageously 'employed'.

resents an acid radical, Y represents a` `The temperatures employed are advantageously -CHz-S- group and Z represents'thenon-mea between 50 C. and 10G? C`.

,35. tallic atoms necessary to complete a hetero'cyclic Cyc'lammcnium quarternary salts containinga 5 s orsi-ct:

reactive alkyl group can be prepared by heating heterocyclic nitrogen bases containing a reactive alkyl group with esters, such as alkyl halides, particularly alkyl iodides, alkyl sulfates and alkyltoluenesulfonates for example, in a manner well known to those skilled in the art. Quaternary salts of heterocyclic nitrogen bases, such as 1- methylbenzothiazole, ,u-methylnaphthothiazoles, Z-methylthiazole, 2,4-dimethylthiazole, 2-methylthe reaction mass is advantageously dissolved in a suitable solvent, such as a lower aliphatic alcohol, and a basic condensing agent added and the reaction mixture gently refluxed until dye formation is complete. Strong tertiary organic bases are advantageously employed. At least one molecular proportion of basic condensing agent is advantageously employed.

The following illustrates the formation of one 1-methyl-5-chlorobenzothiazole, 1 methylbenzoxazole, n-methylnaphthoxazoles, 2,4-dimethyloxazole, 2-methyl-Li-phenyloxazole, l-ethylbenzothiazole, 2,4-dimethylselenazole, 2-methy1-4- phenylselenazole, 2-methylthiazoline, 2-methylselenazoline, 2,3,3-trimethylindolenine, apicoline, ry-picoline, quinaldine, lepidine and 2-methyl5,6benzoquinoline for example, are well known in the art.

e Cyclammonium quaternary salts from heterocyclic nitrogen bases containing a reactive alkyl group and halohydrins are described in the copending application of Leslie G. S. Brooker and Lloyd A. Smith, Serial No. 133,524, filed March 29, 1937. Such `Quaternary salts are advantageously prepared by heating the heterocyclic nitrogen bases with bromohydrins, such as ethylene bromohydrin or propylene bromohydrin, for example. The resulting hydroxyalkyl bromide is advantageously converted to the hydroxyalkyl iodide by treatment with aqueous potassium iodide before employing to prepare my dyes.

Quaternary salts of the 3-alkylthiol compounds y of either I. or II. can also be prepared by heating the 3-alkylthiol compound with esters, such as alkyl halides, particularly alkyl iodides, alkyl sulfates and alkyltoluenesulfonates for example.

The following illustrates the formation of quaternary salts of the 3-alkylthiol compounds:

3.6 g. (1 mol.) of 3-methylthiol-2:4-benzthiazine were reiiuxed with 3.1 c. c. of methyl iodide (4 mols.) on the water bath for several hours and the product left standing for a day. The solid was ether-extracted, and the light brown residue dried. The yield was 1.4 g.

1.95 g. (1 mol.) of 3-methylthiol-2:4-benzthiazine and 0.95 c. c. of methyl sulphate (1 mol.) were heated at 100 for 11/2 hours, when a viscous mass was formed. It was washed with ether, but did not crystallise. Y y

I have found it advantageous to prepare my new dyes by reacting the heterocyclic nitrogen bases containing a reactive alkyl group with` the 3- alkylthiol compounds and with the esters simultaneously. When employing this procedure, a1-

.kyLp-.toluene-sulfonates are advantageously employed. The three reactants, heterocyclic nitrogen base, the B-alkylthiol compound and the ester, are advantageously heated or fused together. After an initial heating of a few hours,

CzHs OSOzOCHs The 3-alkylthiol compounds are prepared as follows: 3alkylthiol2,4benzothiazines by first preparing o-aminobenzyl alcohol through reduction of anthranilic acid. This is advantageously accomplished by electrolytic reduction as described by Mettler in Berichte der deutschen chemischen Gesellschaft, vol. 38, page 1745 (1905). 'Ihe o-aminobenzyl alcohol is then converted into 3-thiol-2,4benzothiazine by treating with alcoholic potassium hydroxide and carbon disulfide. The 3thiol-2,4benzothiazine (thiocumothiazone) is then converted into S-alkylthiol-2,4-benzothiazine b-y alkylation. These latter two steps are described by Paal and Commerell in Ber. 27, 2430 (1894). The following illustrates the alkylation of 3-thiol-2,4 benzothiazine:

5 g. (1 mol.) of 3-thiol-2r4-benzthiazine were dissolved in 60 c. c. of 10% sodium hydroxide solution and to the filtered solution 6 c. c. (2 mols.) of methyl sulphate were gradually added with vigorous shaking. 'Ihe reaction was complete in a half-hour, when the solid was ltered off, washedA with water and dried by heating at 100 in a vacuum. The yield was 4.9 g.

3-methylthio1-1:4-benzothiazine was prepared through the following stages.: o-nitrophenylthioglycollic acid was prepared from o-chloronitrobenzene, thioglycollicv acid and potassium hydroxide in alcoholic solution, according to the method of Friedlnder and Chwala in Monatsh., 1907, 28, 270, who also describe its reduction with tin and hydrochloric acid to 3-ketodihydro-1:4-benzthiazine,

When this compound (7.5 g.) was treated with 4 g. of phosphorus pentasulphide in boiling xylene and the solution so formed extracted with dilute caustic alkali, 3-thiol-124-benzothiazine was obtained as the sodium salt and, by the addition of acid, the free base was liberated. 'Treatment of the sodium salt with methyl sulphate gave 3- methylthiol-l :4-benzothiazine.

The following illustrates the alkylation of 3- thiol-l vzi-benzothiazine:

3 g. (1 mol.) of 3-thiol1:4benzthiazine were dissolvedlin 151e. c. of 5% sodiumhydroxide solution andpurication ofthe. dyes, the following;

examples willxserye to illustratethe mode `of preparing myrnewdyes. These examples; are not intended to limit myinventlon.

EXAMPLE 1.-2,4diethyZthia-2*,4-thiazinocyanine iodide' 135g. (l-moL) of S-methylthiol-Z'A-benzothiazine, 149g.l (l mol.) of l-methylbenzothiazole and 4.04 g. (2 mols.) of'- ethyl-p-toluenesulfonate were fused together at 150 C. for about 3 hours. 'Ihe resulting reaction mass was dissolved in 20 cc. of absolute ethyl alcohol... Dye formation had already taken place, but the reaction was com` pleted. by refluxing with 1.38 cc.4 (1 molt). of triethylamine for about 5 minutes. The resulting cooled solution was treated with. concentrated aqueous potassium iodide and thedye iodide separated from solution. 'I'he--crude-dye iodide was recrystallized from methyl. alcohol and obtained as yellow crystals melting at 263i C. Its ethyl alcoholic solution was intensely yellow. The formula of the dye. is:

According to the nomenclature for cyanine dyes recently proposed for'v Beilst'ei'nsHandbuch der organischen Chemie, the dye is called [4'-ethyl 21,4-benzothiazine- (3) l [2-ethylbenzothiazole- (1)] methine cyanine iodide. v EXAMPLE 2.-4,1'-.dethyl-ZA-thiazmox-Z'cyanine iodide 1.95 g. (l mol.) of'3-methylthiol-2,4-benzothiazine, 1.434 g. (1 mol.) ofV quinaldine and 2 parts of ethyl-p-toluene-sulfonatewere treated as in EX- ampl'e 1. The crude dye iodide thus obtained was twice recrystallized from methyl alcoholand obtained as red-yellow crystals meltingl at 244. C. Its ethyl alcohol solutionA wasl strongly yelloworange. The formula of thedyei's:

I (22H5 k(12H15 lI According to the Beilstein nomenclature, it is called [fi-ethyl-ZA-benzothiazine- (3') l l-ethylquinoline- (21)] methine cyanine iodide. EXAMPLE 3.2,4 -diethyZseZena-`2',4"thiaeinocya nineizodide 1.95 g. (1 mol.) of, B-methylthiol-ZA-benzothiazine, 1.96 g. (lmol.)l of l-methylbenzoselenazole and 4.04' g,.(2` mols.). of ethyl-p-toluenesulfonate were fused;togethe-ratl 160 C. for about 3 hours. The reaction mass was dissolved in 20 cc. of' ethyl alcoholv andthe resulting solution treated with an excess of potassium iodide in concentrated aqueous solution. The dye separated fromthe solution as a yellow solid. It was recrystallized from pyridine and obtained as yellow crystal'smelting at 271 C. The ethyl alcoholic solution of` the dye was intensely yellow. The formula ofthe dye is:

Using thefB'eilstein nomenclature,4 it is called.

[4-ethyl2,4-benzothiazine- (3) l [2-ethylbenzoselenazole-(l) l' methine cyanine iodide.

1.95 g. (l mol.)v of 3-methylthiol-2,4benzothiazine, l.99.g (1 mol.) of 1-methyl5,6benzo benzothiazole (.1-methyl-a-naphthothiazole) 4.04 g. (2 Inols.) of ethyl p-toluenesulfonate were fusedtogether at 160 C. for about 3 hours. The strongly colored melt was dissolved in ethyl alcohol. and treated as inthe above example to prepare the dye-iodide. The, dye-iodide was` recrystallized from pyridine` and. obtained as yellow crystals melting aty 274? C. Its ethyl-alcoholic solution was strong yellow-orange. of this dye is:

C2Hs\I According to theY Beilstein nomenclature, this dye iscalled [.4 -fethyl -2,4f benzothiazine (3) [2- ethyl5,6-benzobenzothiazole(1)l methine cyanine iodide.

1.95. g. (1 mol.) of. 3-methylthiol-2,4-benzothiazine, 1.83 g. (l mol.)` of l-methyl-SA-benzobenzoxazole (2-methyl--naphthoxazole) 4.04 g. (2 mols.) of.ethyl-p-toluenesulfonate were treated in the above. example. The so-obtained dyeiodide was recrystallized from methyl alcohol and obtained` as pale yellow crystals, melting at 249 C. Its ethyl alcoholic solution was clear yellow. The formula for this dye is:

yHa.

According to `tl'ie-Beilstein nomenclature, this -dye is vcalled [4. ethyl.-2,4.-benzothiazi-ne- (3)1-[2- ethyl-3,4-benzobenzoXazole--( 1) l methinecyanine iodide.

3 The formula EXAMPLE 6.--3,4-diethylthiazolino-2',4'-tha2ino-' cyam'ne iodide According to the Beilstein nomenclature it can be called [4-ethyl-2,4benzothiazino- (3) l-[3-ethyltln'azoline-(2)l methine cyanine iodide.

EXAMPLE 7.-'Z,4-dz`methylthia1 ,4 -thiaainocyanine iodide 1.95 g. (1 mol.) of 3-methylthiol-1:ll-benzthiazine, 1.49 g. (1 mol.) of l-methylbenzothiazole and 3.72 g. (2 mols.) of methyl p-toluenesulphonate were heated together on the steam bath for 5 hours. The mass was dissolved in 20 c. c. of hot alcohol, and 3 g. of potassium iodide in 5 c. c. of hot water were added to the solution. The solid which separated was water washed and recrystallised from methyl alcohol. Its ethyl alcoholic solution was intensely yellow, and the formula of the dye is presumed to be, from the method of formation:

My new thiazinocyanine dyes show a novel sensitizing action in photographic emulsions. My invention is particularly directed to the ordinarily employed gelatino-silver-halide emulsions, and especially to gelatino-silver-chloride emulsions. However, my new dyes can be employed in emulsions in which the carrier is other than gelatin, for example, a resinoussubstance or cellulosic derivative which has substantially no deleterious effect on the light-sensitive materials. As silver halide emulsions, I include such emulsions as are commonly employed in the art, for example, silver chloride or silver bromide emulsions which can contain other salts which may be light-sensitive. By way of illustration, the herein described emulsions were prepared employing an ordinary gelatino-silver-chloride emulsion ci ordinary concentration. v

The methods of incorporating dyes in emulsions are simple and well known to those skilled in the art. In practicing my invention, my new dyes are advantageously added to the emulsion in the form of their solutions inappropriate solvents. 'Ihe solvent must, of course, be compatible with the emulsion, substantially free from any deleterious eiTect on the light-sensitive materials and capable of dissolving the dyes. Methanol has proven satisfactory as a solvent for the dyes in practicing my invention. The dyes are advantageously incorporated in the iinished, washed emulsion and should be uniformly distributed throughout the emulsion. The concentration of accentsv the dye in the emulsion can be varied Widely, for example, from about`5 to about 100 mg. of the dyes in about 1000 cc. of flo-wable emulsion. The suitable and most economical concentration for any given emulsion will be apparent to those skilled in the art upon making the ordinary tests and observations customarily used in the art of emulsion making. The concentration of dye will, of course, vary according to the light-sensitive salt employed, and according to the magnitude of sensitizing effect desired.

To prepare a gelatino-silver-halide emulsion, the following procedure is satisfactory:

A quantity of the dye is dissolved in methyl alcohol, acetone or pyridine and a volume of this solution (which may be diluted with water) containingl from 5 vto 100 mg. of dye is slowly addedl to about 1000 cc. of a-gelatino-silver-halide emul-` sion, with stirring. Stirring is advantageously continued until the dye is uniformly dispersed. With the more powerful of my new sensitizing dyes, 10 to 20 mg. of dye per 1000 cc. of' emulsion suiiice to produce the maximum 'sensitizing eielcts with the ordinary gelatine-silver-halide emulsions.

The above statements are only illustrativeland are not to be understood as limiting my invention in any sense, as it will be apparent that these dyes can be incorporated by other methods in the photographic emulsions customarily employed in the art, such, for example, as by bathing a plate or nlm, upon which the emulsion has been coated, in a solution of the dye in an appropriate solvent, although such a method is ordinarily not to be preferred. The claims are intended tol cover any combination of these new dyes with a photographic emulsion whereby the dye exerts a sensitizing eiect upon the emulsion. The sensitized emulsions of my invention can be yconverted into a photographic element by coating out onto a support, such as glass, cellulose acetate, cellulose nitrate, other cellulose derivative or resin in a manner well known in the art. The claims are intended to cover such photographic elements.

'Ihe accompanying drawing is by way of illustration and depictsthe sensitizing effect of four of my new dyes. Each figure of the drawing is a diagrammatic reproduction of a spectrogram showing the sensitivity of an emulsion containing one of my new dyes.n More specifically, in Fig. 1, the curve represents the sensitivity of an ordinary gelatine silver chloride emulsion containing 2, 4- diethyl-5, 6benzothia2,4'-thiazinocyanine iodide. In Fig. 2, the curve represents the sensitivity of an ordinary gelatino-silver-chloride .L

emulsion containing l,4-diethy1-2,4thiazino- 2cyanine iodide. In Fig. 3, the curve represents the sensitivity of an ordinary gelatinosilver-chloride emulsion containing 2,4-diethyl thia-2,4'thiazinocyanine iodide. In Fig. 4, the curve Arepresents the sensitivity of an ordinary gelatino-silver-chloride emulsion containing 2,4- diethyl-3,4-benZoXa-2',4-thiazinocyanine iodide.

Still further examples showing the application of my invention could be cited, but the foregoing will be suicient toteach those skilled in the art the manner in which my invention is carried out and vthe principles of sensitizing photographic emulsions with my new thiazinocyanine dyes.

My new thiazinocyanine dyes are useful in the construction of light .lters They can also be used as Ycoloring mattersA for textiles, particularly cellulose acetate yarn or the like.

What I claim and desire to be secured by Letters Patent of the United States is: 

